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bgpd: Withdraw implicitly old paths from VRFs when import/export list changes

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If we overwrite import/export RT list via route-maps or even flush by using
`set extcommunity none`, then we must withdraw old paths from VRFs to avoid
stale paths.

For example using:

```
router bgp 65500 vrf vrf1
 bgp router-id 10.180.1.1
 !
 address-family ipv4 unicast
  network 192.168.100.100/32 route-map rm
  rd vpn export 65500:10001
  rt vpn import 65500:10000 65500:10990
  rt vpn export 65500:10000
  export vpn
  import vpn
 exit-address-family
exit
!
router bgp 65500 vrf vrf2
 bgp router-id 10.180.1.1
 !
 address-family ipv4 unicast
  rd vpn export 65500:11001
  rt vpn import 65500:11000 65500:11990
  rt vpn export 65500:11000
  export vpn
  import vpn
 exit-address-family
exit
!
route-map rm permit 10
 set extcommunity rt 65500:10100 65500:12990 65500:13990 65500:11990
exit
```

If we strip extcommunities using:

```
route-map rm permit 10
 set extcommunity none
exit
```

or

```
route-map rm permit 10
 set extcommunity rt 65500:10100 65500:12990 65500:13990
```

Routes that are imported with 65500:11990 (192.168.100.100/32 from vrf1)
becomes stale.

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
This commit is contained in:
Donatas Abraitis 2022-06-07 22:12:07 +03:00
parent aa800819cd
commit 3840a8193e
1 changed files with 20 additions and 0 deletions
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20
bgpd/bgp_mplsvpn.c
View File

@ -844,6 +844,26 @@ leak_update(struct bgp *bgp, /* destination bgp instance */
return NULL;
}
/* If the RT was changed via extended communities as an
* import/export list, we should withdraw implicitly the old
* path from VRFs.
* For instance, RT list was modified using route-maps:
* route-map test permit 10
* set extcommunity rt none
*/
if (CHECK_FLAG(bpi->attr->flag,
ATTR_FLAG_BIT(BGP_ATTR_EXT_COMMUNITIES)) &&
CHECK_FLAG(new_attr->flag,
ATTR_FLAG_BIT(BGP_ATTR_EXT_COMMUNITIES))) {
if (!ecommunity_cmp(
bgp_attr_get_ecommunity(bpi->attr),
bgp_attr_get_ecommunity(new_attr))) {
vpn_leak_to_vrf_withdraw(bgp, bpi);
bgp_aggregate_decrement(bgp, p, bpi, afi, safi);
bgp_path_info_delete(bn, bpi);
}
}
/* attr is changed */
bgp_path_info_set_flag(bn, bpi, BGP_PATH_ATTR_CHANGED);